Today I finally got around to installing the mobo of a extra Xbox into a replacment case.

Anyway it went well and works great. But when I turned it on I noticed the fan in the back of the Xbox wasent blowing much air. I was able to turn it up manually in XMBC but that setting dosent seem to matter once you launch a game.

1st question - Does the xbox fan change speed as needed during gameplay?

2nd - I checked all my temps at idle and after 1/2 hour of Just Cause gameplay Are these normal and ok temps for my xbox?

Those temps are fine. I have an 80mm LED fan running at 12v and AS5 on the CPU. My temps are a couple degrees under those, but nothing outstanding. On a side note: 120mm . I'd like to see you fit that.